In a system in which a fuel is reformed by an endothermic reaction so that a reformed gas including hydrogen, etc. is produced to be supplied to an engine as a fuel, by reforming the fuel in the endothermic reaction using an engine waste heat, a waste heat is recovered, and an improvement in efficiency is expected. Also, when a hydrocarbon fuel, such as gasoline, etc., is reformed so as to supply a reformed gas including hydrogen to the engine, a pumping loss reduction, a combustion efficiency improvement, and a combustion rate improvement are enabled, and an improvement in efficiency of the engine is expected. When the reformer is attached to an exhaust pipe of the engine, an exhaust gas temperature of the engine varies according to an operating status of the engine. Therefore, according to conditions, a reforming efficiency varies. Also, when a gas including hydrogen is produced by a reforming reaction, the lower the reaction pressure, the higher the reaction efficiency.
For example, as described in a patent document 1, a conventional engine system with a reformer has a configuration in which the reformer is attached to an exhaust pipe at a position apart from the engine by a predetermined distance, and a reformed gas produced by the reformer is supplied to a suction pipe together with an exhaust gas.